Well for starters, she's a large baby and is never fully satisfied after eating. Her pediatrician even put her on special formula to fill her quicker. Her pediatrician said she could have solids. Just as long as I'm sure to get the appropriate consistency and texture.
Exclusive breastfeeding is recommended until 6 months. Babies can then sit up and feed themselves fork mashed yams, bananas, or avocados. There is no need to "make" baby food. Even if a baby is fed formula it is recommended to wait until around 6 months.
Time for a new doctor! This doctor is not following nutrition guidelines. If she is large you have been feeding her too much. She should get about 32 oz of formula a day. If she wants to suck more she can use a pacifier. Babies aren't developmentally ready for solids at 3 months no matter how big they are. Their gut isn't mature enough.
You can try pears (my daughter LOVES them). You could give her oatmeal cereal also. And just whatever you think she can handle! All babies are different and i had to start mine on solids early because of her staying hungry.